Digital radio broadcasting technology delivers digital audio and data services to mobile, portable, and fixed receivers. One type of digital radio broadcasting, referred to as in-band on-channel digital audio broadcasting (IBOC DAB), uses terrestrial transmitters in the existing Medium Frequency (MF) and Very High Frequency (VHF) radio bands. HD Radio™ technology, developed by iBiquity Digital Corporation, is one example of an IBOC implementation for digital radio broadcasting and reception. IBOC DAB signals can be transmitted in a hybrid format including an analog modulated carrier in combination with a plurality of digitally modulated carriers or in an all-digital format wherein the analog modulated carrier is not used.
One feature of digital transmission systems is the ability to simultaneously transmit both digitized audio and data. Thus the technology also allows for wireless data services from amplitude modulation (AM) and frequency modulation (FM) radio stations. The broadcast signals can include metadata, such as the artist, song title, or station call letters. Special messages about events, traffic, and weather can also be included. For example, traffic information, weather forecasts, news, and sports scores can all be scrolled across a radio receiver's display while the user listens to a radio station.
Using the hybrid format, broadcasters may continue to transmit analog AM and FM simultaneously with higher-quality and more robust digital signals, allowing themselves and their listeners to convert from analog-to-digital radio while maintaining their current frequency allocations. Using the all-digital format, additional data channels are available for broadcasters to transmit more data with the audio program.
An IBOC DAB radio system allows multiple services to share the broadcast capacity of a single station. One feature of digital transmission systems is the inherent ability to simultaneously transmit both digitized audio and data. Thus, one station can provide a Main Program Service (MPS), supplemental program service (SPS), and information services for, among other things, multicast programming, electronic program guides, navigation maps, traffic information, multimedia programming and other content. However, a challenge in providing digitized audio is reception for mobile radio receivers. Impairment of reception of the radio signal can negatively impact the experience of a user.